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Recording & Storage Media

Storage

CD/DVD

CDs and DVDs are optical storage discs holding roughly 700MB and 4.7GB of data respectively. A second generation DVD called a dual layer DVD can hold approximately 8.54GB of data. Both the CD and the DVD come in write-able versions which can be recorded to once, as well as re-writeable versions which can be recorded-erased-recorded again some limited number of times.

In 2006 the Blu-Ray DVD was created with a memory capacity ranging from 50-100GB of high-definition video, although in order to realize its full benefits the video must be viewed through a high-definition TV. Even though the presence of recordable CD and DVD writers has increased immensely, there is some uncertainty as to the long-term archival quality of optical discs.

USB

USB is actually a data transfer protocol often used in reference to the way in which a particular storage device attaches to a computer. For example, a USB thumb drive is a Flash memory device which attaches to a USB port to allow the transfer of data. USB hard drives attach via a USB port as well, just with greater storage capacities. There are several USB standards at this time but basically USB 1.1 allows for 12 Megabits per second (Mbps) of data transfer speed while the more common USB 2.0 standard allows for 480 Mbps. Currently in the works and just starting to appear on higher end enthusiast motherboards are the USB 3.0 ports. USB SuperSpeed 3.0 allows for data transfer rates in the neighborhood of 4.8 Gigabits per second.

Flash

Flash memory is a type of non-volatile memory which means it does not lose its content when power is removed. This, and the fact of it allowing for fairly fast read access makes it a convenient storage device used in digital still cameras, video cameras, MP3 players, cell phones, etc.

HDD

Hard Drives as typically found in computers, use magnetic disc technologies to store and retrieve data. As costs have come down, storage capacities have increased greatly. One or two Terabyte (TB) hard drives are not uncommon at this time. Serial Advanced Technology Attachment (SATA) interfaces allow 3GB/sec. data transfer rates. Also available are external hard drives which typically connect via a USB port, but transfer data at much slower rates.

The following table outlines the comparisons:

VHS

VHS is the magnetic tape storage system developed in the mid 1970's. Although still around, it has largely been supplanted by optical disc technology, namely the DVD and Blu-ray.

Video Codecs

• H.264 - This MPEG 4 Part 10 standard is a very high quality video compression technique developed in 2003. It is currently the video format found in Blu-ray DVD, digital satellite and cable service, as well as Apple's latest Quicktime format. A 1080p Blu-ray DVD runs at approximately 250-400MB per minute of video.
• DivX / XviD - The MPEG 4 Part 2 standard is a high quality video compression technology. Two of the more popular formats in this category are DivX and XviD. Medium quality DivX files currently contain about 21 Megabytes (MB) of video per minute.

Video Formats

•  NTSC - NTSC refers to the TV and video standard common to the United States, Japan, South America and some parts of Asia. NTSC video is transmitted at 30 Frames Per Second (FPS) with 525 individual scan lines per video frame
•  PAL - PAL is the video system used in the rest of the world. PAL video is transmitted at 25 FPS with each video frame comprised of 626 scan lines.

Still Image Formatting

• TIFF is a lossless photographic file format offering the best image quality at the cost of fairly large file sizes.
• JPEG is a lossless file format for images. The amount of compression is adjustable but there is a trade-off between file size and image quality. Obviously, the more compression one uses (which looses image data) the lower the quality of the image.
• BMP is a lossless image file format similar to the TIFF format but results in file sizes much larger than the TIFF format.

Monitors

Resolution - The term resolution, as commonly applied to LCD monitors and CRT displays, refers to the number of distinct pixels able to be displayed in each direction. The standard resolution in the US is 720 x 480. High definition 720p video is considered 1280 x 720 and 1080p is 1920 x 1080.

Aspect Ratio - Standard NTSC video in the US has an aspect ratio of 4:3. This number refers to the ratio comparing the width of an image to its height. Widescreen, high-definition TV's, and computer monitors typically have a 16:9 aspect ratio.

Cathode Ray Tube (CRT) refresh rates refer to the number of times per second the hardware redraws to the screen. Too low a refresh rate and the eye will notice flicker. Too high of refresh rate could overtax the video hardware and theoretically cause damage.

Liquid Crystal Display (LCD) monitors have a fixed refresh rate but have to contend with response times. Response time of an LCD is measured as the time for a pixel to go from black to white and then back to black. Obviously the faster the response time an LCD has the less the viewer will notice any motion artifacts. Video with large amounts of motion requires a display with fast response times.

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